Hepatitis B in men who have sex with men and HIV-infected individuals: missed opportunities and future challenges

Abstract

Hepatitis B transmission in priority populations continues to occur in Australia despite the availability of a safe, effective vaccine for over 30 years. In this edition of Sexual Health, Body et al. report an incidence of 1.8 hepatitis B virus (HBV) infections per 1000 person years in the Victorian HIV database (VHIVSD), a cohort of HIV-infected individuals receiving care at a tertiary referral hospital in Melbourne. A similar incidence of infection (1.98 per 1000 person-years) was found by Gamagedara et al. among men who have sex with men (MSM) attending a community sexual health centre, also in Melbourne. This incidence of infection is more than 10 times the estimated incidence in the general population and is evidence of ongoing transmission in these priority populations despite being part of clinical cohorts and therefore occurring in people linked to care. Both of these recent studies highlighted missed opportunities for screening, vaccination and follow-up testing to ensure the protection of individuals at particular risk of HBV infection. This new evidence reinforces the need for a greater focus on comprehensive testing and vaccination of priority populations, including HIV-infected individuals and MSM – particularly given recent reports of increasing sexual risk practices in MSM and corresponding increases in sexually transmissible infections, including HIV. With an estimated 218,00 people (1.0% of the population) living with chronic hepatitis B (CHB) in 2011, Australia is generally a low-prevalence country, with the main burden of disease experienced by those born overseas in endemic areas, and by Aboriginal and Torres Strait Islander people. MSM are estimated to account for ~4.4% (around 9700 individuals) of those living with CHB and are identified as a priority population for prevention of infection in the First National Hepatitis B Strategy 2010–2013. The higher incidence of acute HBV infection and prevalence of CHB in HIV-infected individuals and MSM is multifactorial. The increased incidence of infection relates to shared modes of transmission, including sexual, injecting drug use or both. Globally, areas with a high or increasing population prevalence of HIV are often also endemic for CHB, making coinfection with HBV more common in HIV-infected individuals born in these countries who now reside in Australia. HIV infection is associated with both an increased risk of developing CHB if exposed to HBV and an increased risk of complications, including cirrhosis and liver cancer. In the retrospective cohort reported by Body and colleagues, 23% of patients with incident HBVinfection went onto to develop CHB – far greater than the expected 5% progression observed in immunocompetent adults. Both studies highlight the need for further improvements in access to HBV testing. In the study reported by Gamagedara et al., ascertainment of immunity status was high but markers of infection were less commonly tested: hepatitis B surface antibody (anti-HBs) was tested in 96% of patients, compared with testing for core antibody (anti-HBc) in 79% and surface antigen (HBsAg) in 26% of patients. As the authors comment, incomplete testing raises the possibility of missed incident and chronic infections. Similarly, Body et al. report that HBsAg and anti-HBc testing were not performed in 32% of HIV-positive individuals. The National Hepatitis B Testing Policy released in 2012 recommends testing for all three markers of HBV infection in those at higher risk of CHB, including MSM and HIVinfected individuals. The use of alternative screening algorithms can lead to missing chronic infections, and creates the need for unnecessary vaccination, recall and repeat testing of individual patients. The panel of three tests (HBsAg, anti-HBs and anti-HBc) is Medicare rebatable and is advised for any person at risk of having CHB. For individuals in the VHIVSD in whom HBV infection was documented, the median estimated time between HIV diagnosis and HBV infection was 4.6 years (range: 4 months to 17 years). These results indicate missed opportunities for prevention through vaccination, and suggest infrequent routine testing to determine anti-HBs status and promote vaccination. Together, they suggest that the prevention of HBV infection in HIVinfected individuals needs greater attention. Vaccination is recommended for susceptible MSM and HIVinfected individuals. However, eligibility for a funded CSIRO PUBLISHING